Do not delay in making VISA arrangements for entry into the United States if needed. Such arrangements are the responsibility of attendees and other participants and may take up to several months. Depending on country of origin and length of stay in the United States, you may or may not require a VISA to enter the country.
How to Obtain a Visa
Complete information on VISA requirements, and if needed, how to apply for a VISA to enter the United States can be found on the US Government website.
Download your generic invitation letter.